What Is Water Lettuce?

Water lettuce is an aquatic plant that looks a bit like a very loose head of romaine lettuce floating on top of the water. Considered invasive in many areas with wetlands, lakes, and ponds, this plant is often a favorite among aquatic gardeners. It usually grows quickly, covers a lot of surface area, and needs very little care. Those with fish might also grow it to supplement the animals’ diets. This plant usually only grows in relatively mild climates, so those who live in climates with extreme seasonal changes may want to grow water lettuce indoors or as an annual.

Many gardeners believe water lettuce looks like a cross between a large, lacy rose and a very green head of cabbage. These plants feature a very tight central cluster of leaves surrounded by broad, thick, scalloped leaves. They usually grow very quickly, with each parent plant sprouting a young plant within a week or two of maturation. In the space of a month, a gardener might have enough water lettuce plants to cover a small pond. This fast growth cycle is often the reason water lettuce is classified as invasive. If it grows uncultivated, it can take over very large bodies of water within the space of a summer.

Those interested in planting water lettuce may be pleasantly surprised at how easy it usually is. These plants generally grow best in a confined area because they like to overlap and brush against one another. A pond with a limited number of fish in it, or a planter with nutritious soil in the bottom, often works well. Gardeners may also simply pour water into a large planter and treat it with a capful or two of liquid fertilizer. Seaweed fertilizer works well, as do fertilizers formulated for aquarium plants. Water lettuce may need to be fertilized each week because its root system is often very large.

Planting water lettuce is usually a simple matter of gently clipping away any brown or yellow leaves, and setting each rosette roots-down in the water. This works best if the young root system is about the size of the gardener’s palm. Plants with smaller root systems should typically be placed in the center of a floating foam ring so they don’t fall over and begin to rot. Young plants should also be shaded by trees or a lightweight awning of some kind. When the plants grow to about the size of two fists pressed together, they may be exposed to full sunlight.